Dye surface coating enables visible light activation of TiO2 nanoparticles leading to degradation of neighboring biological structures

Composition of the metabolomic bio-coronas isolated from Ocimum sanctum and Rubia tinctorum

Objective

Nanoharvesting from intact plants, organs, and cultured cells is a method in which nanoparticles are co-incubated with the target tissue, which leads to the internalization of nanoparticles. Internalized nanoparticles are coated in situ with specific metabolites that form a dynamic surface layer called a bio-corona. Our previous study showed that metabolites that form the bio-corona around anatase TiO₂ nanoparticles incubated with leaves of the model plant Arabidopsis thaliana are enriched for flavonoids and lipids. The present study focused on the identification of metabolites isolated by nanoharvesting from two medicinal plants, Ocimum sanctum (Tulsi) and Rubia tinctorum (common madder).

Results

To identify metabolites that form the bio-corona, Tulsi leaves and madder roots were incubated with ultra-small anatase TiO₂ nanoparticles, the coated nanoparticles were collected, and the adsorbed molecules were released from the nanoparticle surface and analyzed using an untargeted metabolomics approach. Similar to the results in which Arabidopsis tissue was used as a source of metabolites, TiO₂ nanoparticle bio-coronas from Tulsi and madder were enriched for flavonoids and lipids, suggesting that nanoharvesting has a wide-range application potential. The third group of metabolites enriched in bio-coronas isolated from both plants were small peptides with C-terminal arginine and lysine residues.

Toxicity of engineered nanomaterials with different physicochemical properties and the role of protein corona on cellular uptake and intrinsic ROS production

The Organisation for Economic Co-operation and Development has listed thirteen engineered nanomaterials (ENM) in order to investigate their toxicity on human health. Silicon dioxide (SiO₂) and titanium dioxide (TiO₂) are included on that list and we added indium tin oxide (ITO) nanoparticles (NPs) to our study, which is not listed on OECD suggested ENM to be investigated, however ITO NPs has a high potential of industrial production. We evaluate the physicochemical properties of SiO₂ NPs (10-20 nm), TiO₂ nanofibers (NFs; 3 μm length) and ITO NPs (<50 nm) and the impact of protein-corona formation on cell internalization. Then, we evaluated the toxicity of uncoated ENM on human lung epithelial cells exposed to 10 and 50 μg/cm² for 24 h. TiO₂ NFs showed the highest capability to adsorb proteins onto the particle surface followed by SiO₂ NPs and ITO NPs after acellular incubation with fetal bovine serum. The protein adsorption had no impact on Alizarin Red S conjugation, intrinsic properties for reactive oxygen (ROS) formation or cell uptake for all types of ENM. Moreover, TiO₂ NFs induced highest cell alterations in human lung epithelial cells exposed to 10 and 50 μg/cm² while ITO NPs induced moderated cytotoxicity and SiO₂ NPs caused even lower cytotoxicity under the same conditions. DNA, proteins and lipids were mainly affected by TiO₂ NFs followed by SiO₂ NPs with toxic effects in protein and lipids while limited variations were detected after exposure to ITO NPs on spectra analyzed by Fourier Transform Infrared Spectroscopy.

Uptake and toxicity studies of magnetic TiO2-Based nanophotocatalyst in Arabidopsis thaliana

Information on the environmental impact of magnetic TiO₂-based nanophotocatalysts is scarce. This study evaluated the potential effects of an innovative magnetic nanophotocatalyst N-TiO₂/Fe₃O₄@SiO₂ (NTFS) on plants using Arabidopsis thaliana grown in a hydroponic system. NTFS was detected in the vascular tissues and mesophyll of plants, thus confirming the uptake and upwards transport of NTFS from roots to leaves. Fourier transform infrared spectroscopy was applied to determine compositional and structural alterations in plant tissues exposed to NTFS, or its two main components (N-TiO₂ and Fe₃O₄@SiO₂), at concentrations ranging from 0 to 1000 mg/L, but no changes were detected in the lipids, pectins, proteins, cellulose, hemicellulose, and carbohydrates. The morphology and biomass of the plants were not affected by the NTFS or its components either. Biosensors for inorganic phosphate (Pi) and MgATP^2- were used to monitor the in vivo Pi and MgATP^2- levels in the plant cells. The results showed that NTFS and its components did not induce any adverse effects on the cytosolic Pi level or ATP synthesis, indicating the energy physiology of Arabidopsis was unaffected. In general, NTFS has inconsequential toxic effects on Arabidopsis, but can be taken up by plants, enter the food chain, and cause potential exposure and bioaccumulation in animals and human beings.

Emerging Nanotechnology and Advanced Materials for Cancer Radiation Therapy

Radiation therapy (RT) including external beam radiotherapy (EBRT) and internal radioisotope therapy (RIT) has been widely used for clinical cancer treatment. However, owing to the low radiation absorption of tumors, high doses of ionizing radiations are often needed during RT, leading to severe damages to normal tissues adjacent to tumors. Meanwhile, the RT efficacies are limited by different mechanisms, among which the tumor hypoxia-associated radiation resistance is a well-known one, as there exists hypoxia inside most solid tumors while oxygen is essential to enhance radiation-induced DNA damages. With the development in nanotechnology, there have been great interests in using nanomedicine strategies to enhance radiation responses of tumors. Nanomaterials containing high-Z elements to absorb radiation rays (e.g. X-ray) can act as radio-sensitizers to deposit radiation energy within tumors and promote treatment efficacy. Nanoscale carriers are able to deliver therapeutic radioisotopes into tumors for internal RIT, or chemotherapeutic drugs for synergistically combined chemo-radiotherapy. As uncovered in recent studies, the tumor microenvironment could be modulated by various nanomedicine approaches to overcome hypoxia-associated radiation resistance. Herein, the authors will summarize the applications of nanomedicine for RT cancer treatment, and pay particular attention to the latest development of 'advanced materials' for enhanced cancer RT.

Cellular uptake and cytotoxicity of a near-IR fluorescent corrole-TiO2 nanoconjugate

We are investigating the biological and biomedical imaging roles and impacts of fluorescent metallocorrole-TiO2 nanoconjugates as potential near-infrared optical contrast agents in vitro in cancer and normal cell lines. The TiO2 nanoconjugate labeled with the small molecule 2,17-bis(chlorosulfonyl)-5,10,15-tris(pentafluorophenyl)corrolato aluminum(III) (1-Al-TiO2) was prepared. The nanoparticle 1-Al-TiO2 was characterized by transmission electron microscopy (TEM) and integrating-sphere electronic absorption spectroscopy. TEM images of three different samples of TiO2 nanoparticles (bare, H2O2 etched, and 1-Al functionalized) showed similarity in shapes and sizes with an average diameter of 29nm for 1-Al-TiO2. Loading of 1-Al on the TiO2 surfaces was determined to be ca. 20-40mg 1-Al/g TiO2. Confocal fluorescence microscopy (CFM) studies of luciferase-transfected primary human glioblastoma U87-Luc cells treated with the nanoconjugate 1-Al-TiO2 as the contrast agent in various concentrations were performed. The CFM images revealed that 1-Al-TiO2 was found inside the cancer cells even at low doses (0.02-2μg/mL) and localized in the cytosol. Bioluminescence studies of the U87-Luc cells exposed to various amounts of 1-Al-TiO2 showed minimal cytotoxic effects even at higher doses (2-2000μg/mL) after 24h. A similar observation was made using primary mouse hepatocytes (PMH) treated with 1-Al-TiO2 at low doses (0.0003-3μg/mL). Longer incubation times (after 48 and 72h for U87-Luc) and higher doses (>20μg/mL 1-Al-TiO2 for U87-Luc and >3μg/mL 1-Al-TiO2 for PMH) showed decreased cell viability.